The invention relates to an apparatus for cutting to length the connecting wires of electrical components, the apparatus comprising a component guide and a cutting device arranged below the component guide.
Electrical components such as resistances, capacitors, transistors, diodes etc are normally supplied by the manufacturer provided with connecting wires which have a considerable amount of oversize and have to be cut by the user to the size necessary for the particular use intended in a specific circuit arrangement. In apparatus of the type initially described above, which are known (from actual practice) and carry out this task, the components are introduced individually by hand into a component guide which usually consists essentially of holders for the connecting wires which are to be cut to the desired length. Below the component guide there is arranged at the necessary spacing a cutting device which shortens the connecting wires to the intended size. Then the component processed is taken from the component guide and a new component for cutting to the desired length is introduced. These known apparatus allow only a relatively slow throughput of components and involve considerable expense on labor.
Apparatus of another kind are also known (compare German laid-open specification No. 24 00 307) which have a different construction and are not arranged simply for cutting to length the connecting wires of electrical components but also bend the connecting wires and provide them with bent portions or corrugations. However, these apparatus of a different category are suitable only for dealing with components which have coaxially arranged connecting wires. Components which have a plurality of connecting wires arranged at one side of the component body or in a completely irregular manner cannot be processed with this kind of apparatus. An object of the invention is to provide an apparatus of the kind described initially above whereby it is possible with a small expense on labor, that is to say with very substantial automation, to cut the connecting wires to the intended size with a good standard of precision, and with a high throughput of components. A more specific object is to provide such apparatus which can be made robustly and to operate in a trouble-free manner and which can be used for a wide range of wire diameters.
To this end, according to the present invention, the component guide consists of a slideway which comprises a guide slot through which the connecting wires can extend downwardly, the cutting device comprises two shearing wheels which are each provided with a peripheral cutting edge and at least one of which is adapted to be driven in rotational movement, the shearing wheels are arranged with the peripheral cutting edges abutting on one another and being arranged to partly overlap one another, and at least the front intersection point of the peripheral cutting edges, considered in the direction of rotation of the driven cutting wheel, is situated below the guide slot.
In use of apparatus according to the invention, components are continuously fed-in by the slideway, and the connecting wires which are to be cut to length extend downwardly through the guide slot and come into the working region of the cutting device. The latter consists of two shearing wheels. At least one of these, that which is referred to hereinafter as the working wheel, is adapted to be driven in rotational movement by a motor whilst the other wheel, referred to hereinafter as the co-operating wheel, usually does not have any drive of its own. From the partly overlapping arrangement of the shearing wheels it follows that their peripheral cutting edges intersect at two points. The arrangement is made such that the peripheral speed of the working wheel at the forward of the two intersection points has at least one component which is parallel to the guide slot and in the direction of conveyance of the electrical components, so that these are drawn into the angle between the shearing wheels at the front intersection point and are cut off by the peripheral cutting edges abutting on one another. In order that this should take place smoothly it is provided that at least the forward point of intersection is situated below the guide slot, in other words in the slot plane. Within the framework of the invention what is understood as the slot plane is a plane which contains the guide slot and is situated at right angles to the boundaries of the guide slot; in other words, the connecting wires of the fed-in electrical components are normally situated in the slot plane.
A symmetrical arrangement, which is particularly simple from the constructional point of view, is achieved if the axes of rotation of the shearing wheels are so arranged relatively to the guide slot that the common chord of the shearing wheels (which connects the points of intersection) is situated below and in the direction of the guide slot. In some cases it may also be advisable to have an arrangement wherein the guide slot in the region of the front point of intersection of the peripheral cutting edges extends approximately tangentially relatively to the upper shearing wheel. With such an arrangement the result is achieved that the connecting wires, after being cut to length, can pass the upper shearing wheel without substantial lateral deflection, so that a particularly uniform, smooth passage of the electrical components through the apparatus is achieved.
It is advisable to arrange the shearing wheels with their axes parallel to one another so that they abut on one another with flat faces directed towards one another. Preferably the non-driven shearing wheel, i.e. the co-operating wheel, is mounted to be freely rotatable and bears on the working wheel under the action of gravitational force and/or spring action, but at any rate yieldably. This is particularly simple to arrange constructionally, results in an extremely reliable cutting-off of the connecting wires, and also has the result that the peripheral cutting edges are always kept sharp.
In order that the connecting wires are engaged and sheared off reliably, the arrangement should be such that the tangents of the shearing wheels form an acute angle with one another at the points of intersection. But this kind of arrangement makes it necessary to have a cutting device of relatively large dimensions, which is in many cases undesirable, and yet often still does not ensure a completely smooth operation. Therefore, according to the invention it is also proposed that the working wheel comprises serrations at its periphery whilst the co-operating wheel is usually provided with a smooth peripheral contour. The connecting wires are engaged by the serrations and effectively guided against the co-operating wheel with a shearing action. The serrations provided are preferably not the usual "teeth" as on a gear wheel, and on the contrary it is advisable to form the serrations as a knurling which is coarse relative to the diameter of the connecting wires which are to be cut. The contour of the knurling consists preferably of triangles following one another and provided with substantially straight boundaries. "Coarse" means that the depth between the serration projections of the knurling corresponds, as regards the order of magnitude, to the wire diameter. This depth is not particularly critical, and it is readily possible to cut all wire diameters which are likely to occur in actual practice with a suitably selected serration arrangement. The flank angle of the serration projections depends in more detail on the diameter and arrangement of the shearing wheel and is preferably not chosen with too acute an angle, so that a pulling cut is carried out on all wire diameters without any great impact stresses. It has also been found advantageous to construct the co-operating wheel as a truncated cone which widens slightly towards the working wheel so that the peripheral cutting edge is slightly acute-angled in cross-section. This results in a still quieter cut without much impact load.
In a particularly advantageous constructional form of an apparatus according to the invention it is proposed that the shearing wheels are mounted in a drive block--preferably at the top of the said block--and the said block can be lifted and lowered relatively to the guide slot. Usually the drive motor for the working wheel is also flange-mounted on the drive block. For lifting and lowering the drive block can be guided on guide rods and adjusted by means of a spindle which is integral with the housing and a spindle nut which is adapted to rotate in the drive block. By means of these measures the connecting wires can be cut to an adjustable length. It is also advantageous to provide the drive block with a longitudinal slot which is associated with the guide slot and in which the connecting wires can be guided when being fed to the cutting device. Downstream of the shearing wheels, as considered in the direction in which the electrical components are conveyed, the longitudinal slot opens downwardly into a discharge and/or reception container for the cut-off ends of wire, this being a particularly advantageous feature which ensures in a particularly simple manner that the cut-off wire ends are not scattered in an uncontrolled manner and thereby possibly causing a blockage or other operational disturbance.
Uniform feeding of the electrical components can be achieved in various ways. A first possible method is to arrange the guide slot of the slideway for the components with a downward gradient towards the shearing wheels, so that the said components are fed onwards by the action of gravitational force. For this purpose, for example, the entire apparatus including the cutting device can be set up with a suitable and preferably adjustable inclination. The slideway can also consist of two parallel, flexible, spring steel rails which are arranged with a spacing and which, with the cutting device stationary, can be lifted or lowered as required and in any case ensure a transition without any break to the cutting device. On the other hand--particularly in the case of high operating speeds--it may be advantageous to connect-on a special conveying means, for example in the form of a shaker conveyor, vibrator or the like. A further possibility which is particularly suitable in conjunction with an inclined guide slot is to arrange above the guide slot, in the region of the shearing wheels, a conveying roller which can be driven in rotary movement about an axis which is perpendicular to the plane of the slot. This results in the first instance in a uniform feeding of the components, and in addition the conveying roller at the same time acts as a device for holding the workpiece down during cutting, so that in spite of the shock which is not completely avoidable it is possible to provide satisfactory guiding. Of course the conveying roller rotates in the direction in which the components are conveyed, and preferably consists of a soft elastomer, foamed plastics material or the like, and in one preferable constructional form is arranged to be vertically adjustable in accordance with the dimensions of the components. A further and particularly inexpensive measure for improving the guiding of the components consists in arranging guide rails at an adjustable spacing at both sides of the guide slot at least in the region of the shearing wheels. This measure also has the result of inhibiting uncontrolled movements of the components in the region of the cutting device.
The apparatus according to the invention requires only little constructional expense and makes it possible for the connecting wires of electrical components to be cut to the intended length simply and reliably. It does not require any manual intervention once it has been set, and it operates continuously with a very high throughput of components. Thus the apparatus according to the invention allows a considerable rationalisation in the preparation of electrical components for building into circuit arrangements, and is particularly suitable as a component part of a unit construction system which includes other processing apparatus such as apparatus for bending the connecting wires, shaping them with bends or corrugations, etc.